Some intra-body medical probes, such as cardiac catheters, transmit data over a wireless channel in order to reduce cabling. Several methods and systems for controlling such probes are known in the art. For example, U.S. Patent Application Publication 2010/0056871, whose disclosure is incorporated herein by reference, describes a method for device control. The method includes bringing a plurality of medical devices into contact with a body of a patient. The medical devices are coupled to communicate with a console via a digital interface. A message is transmitted over the digital interface from the console, to be received simultaneously by the plurality of the medical devices. The medical devices are synchronized with one another responsively to receiving the message. In some embodiments, signals are sampled using a respective internal clock in each of the medical devices, and the medical devices are synchronized by resetting the internal clock.